1. Field of the Invention
The present invention relates to an apparatus and method for depositing a magnesium oxide film on a substrate, and more particularly, in order to increase the deposition speed of a magnesium oxide (MgO) film using magnetron sputtering discharge developing a new power supply system and its utilizing process to form a MgO film on a plasma display panel (PDP) of 40 to 100 inch in size.
2. Description of the Related Art
In the field of PDP technology, MgO is commonly used as a protective film or an electron release medium. The MgO film is formed by means of physical deposition such as sputtering, thermal deposition, and electron beam evaporation, or metal-organic chemical vapor deposition (MOCVD) by chemical reaction between gaseous reactants. The Korean Patent Publication No. 2002-0088127, Lee and Park, discloses a method of forming a film through MOCVD. MOCVD allows very rapid film formation but has problems such as a comparatively complicated process and a rather high incidence of defective quality.
With deposition using a sputtering method, the deposition process is relatively simple and impurity content in the formed film is very low compared to the MOCVD although the film growth speed is slow. Therefore, if the film growth speed can be increased, the deposition by sputtering may provide a MgO film with good quality and higher productivity.
The Korean Patent Publication No. 2001-0025739, Choi et al., discloses an apparatus and method for depositing MgO film using magnetron-sputtering discharge. The power supply used in the above-mentioned patent publication provides high-frequency waves oscillating from plus polarity to minus polarity. The used frequency is normally between 10 kHz and 13.56 MHz. However, the power supply has a limitation on the increase of MgO film growth speed because ions colliding with magnesium targets cannot obtain enough energy due to wave characteristics of oscillating from plus polarity to minus polarity and self-bias by electrons on the surface of the magnesium targets.
In addition, when a plurality of magnesium targets are arranged in parallel and power is applied to the magnesium targets to generate discharge, the generated discharge may disappear during the operation because power oscillation from plus polarity to minus polarity causes interference between magnesium targets. Therefore, an auxiliary equipment is required to prevent the disappearance of the discharge.